Background

High-quality water sources may be required only for drinking
purposes, while the quality of water for other domestic uses can be
quite variable. Therefore, water polluted to only a certain extent can
be considered pure [1].
With an increasing urban population density of the study area, the
scarcity and pollution of surface water poses a serious problem for
urban drinking water supplies of metropolitan areas [2-7]. Consequently, water resources are a key factor, particularly for planning a sustainable socioeconomic development [8,9].
Bottled water, however, is being widely consumed because it contains
fewer impurities. Therefore, it can also be beneficial to detect
deterioration in the quality of water resources and to facilitate
appropriate and timely corrective actions with a minimal negative
impact on public health [10-14].

For the last three decades, many countries in arid and semi-arid
regions have depended heavily on the desalination of seawater to meet
their growing needs. Saudi Arabia is considered one of the biggest
efficient producers of freshwater by desalination, with an installed
capacity of more than 1000 million USGPD, accounting for 24.4%> of
the world's desalinated water production [15,16].
In the case of Saudi Arabia, surface water sources (i.e. dams, lakes,
and open water reservoirs) are considered to be very limited resources
and are exploited for almost every use. They are also exposed to urban
wastewater disposal from both wastewater stations (that has not reached
secured stages 3–4 in most of the Saudi wastewater stations 70%,
causing an expected environmental pollution especially around
metropolitan areas), which has made the surface water resources highly
polluted, especially in parched valleys. The frequent outbreaks of
waterborne diseases are the result of a direct discharge of untreated
or partially treated domestic sewage water sources located beside local
gutters [1,17,4].

Groundwater is still and will continue to be the main source of safe
and reliable drinking water, especially in rural areas in Saudi Arabia.
Water taken from such sources (different types of shallow and deep
wells) is often of better quality than surface water or other open
water sources if the soil is fine-grained and its bedrocks do not have
cracks, crevices, and bedding plants, which permit the free passage of
polluted water especially within metropolitan zones [7,30,37,7,20].
It is often assumed that natural, uncontaminated water from deep wells
is clean and healthy, and this is usually true with regard to
bacteriological composition [21].
However, bacterial pollution of water sources may occur and is mostly
derived from watershed corrosion as well as drainage from sewage,
swamps, or soil with a high humus content. This type of hazard exists
particularly in limestone areas where underground chambers or fissures
may permit water to flow in the freely moving streams without
substantial filtrations. Such suspected water sources cannot be used
without caution for human drinking purposes because of the inherent
health risks [22,16,17,24,4-7,11].

The major interest of public health authorities in developing
quality standards for urban water uses is focused on the recognition,
enumeration, identification, and assessment of microorganisms related
to waterborne diseases that are considered indicators of
microbiological parameters [25,17,5,7,11,26]. These indicators are of great importance to assess the microbial condition of the examined water sources [27].
Moreover, the bio-indicator of faecal pollution is a non-pathogenic
microorganism, whose detection suggests the presence of enteric
pathogens. Usually, coliforms, faecal coliforms, and faecal
streptococci are recognised as the main indicators of microorganisms in
water sources [26,9]. These indicators are of significance to assess the microbial condition of the water supply [28]. Microorganisms as an indicator of faecal pollution should satisfy several criteria [29,20].
For instance, they should be present in faeces in greater numbers and
have more resistance than any pathogen to the stresses of an aquatic
environment [30,31,17,4,26]. The evaluation of total coliforms may sometimes give erroneous information regarding faecal contamination [32,17,4,11,26,12].

The main objective of this study was to assess the bacteriological
water quality and its geospatial relations of the four major urban
water sources in the study area (bottled, desalinated, surface, and
well water) which have been the focus of the community [23,5-7]. An attempt was also made to identify the coliforms isolated from the examined water samples (Table 1).
The findings may be considered as a basis for water health policy
decisions at different administrative levels in the study area.